NIRT: One-,Two- and Three-Dimensional Superstructured Materials from Well-Defined, Complex Nanoscale Components

Washington University, Saint Louis MO

Investigators

Abstract

This Nanoscale Interdisciplinary Research Team (NIRT) project, co-funded by the National Science Foundation Divisions of Materials Research, Chemistry, and Chemical and Transport Systems, will develop synthetic strategies and characterization protocols for the production and study of one-, two- and three-dimensional superstructures composed of stabilized nanoparticle assemblies. The synthetic approach involves the systematic ordering, in solution and on substrates, of crosslinked assemblies of copolymers, as robust core-shell building blocks, to manufacture 1-dimensional meso-scale (~100 nm to ~1 mm), 2-dimensional micro-scale (~1 mm to ~100 mm) and 3-dimensional macro-scale (>100 mm) objects, each comprised of nanoscopic building blocks. The result will be the creation of entirely unique composite morphologies that are not accessible in the phase diagrams of the copolymers directly. This strategy mimics the control of chemistry at the nanometer scale that is currently the exclusive province of living systems. Utilization of the nanoscale organic-based superstructures as scaffolds for the initiation of nanocrystalline growth of inorganic materials and biomacromolecules will be a key goal of the investigation. The mechanisms by which the organic superstructures promote crystallization and co-crystallization will be studied in detail. The hypotheses to be tested include: (1) organic nanoparticles will be assembled into well defined one-, two- and three-dimensional superstructures, suitable for fabrication into useful device applications; (2) such superstructures will present interfacial contacts that template the crystallization events to produce unique and controllable nanocrystalline phases, initiated from a surface or via co-crystallization; (3) the nature of the organic superstructures and the nanocrystalline materials will result in unique physical, optical, magnetic, and mechanical properties. The educational and research aspects of the proposed activities will cross several disciplines (organic chemistry, biology, physical chemistry, polymer physics, chemical and mechanical engineering, and materials science) to address effectively the study of one-, two-, and three-dimensional superstructures, composed of two or more nanoscale constructs, and of templated inorganic/organic nanocrystalline materials. The proposed research is rich with opportunities to impact education. Students will benefit through interdisciplinary, multi-site research activities. An outreach course developed (Fall 2001) at Washington University for K-8 teachers will be enhanced and implemented at the participating institutions. The focus of this NIRT also creates an effective platform for societal education of the benefits of nanoscience and nanotechnology. For example, the proposed nanostructured solids may represent new advanced materials for medicine, such as "smart" hydrogel-like coatings for controlled release of drugs, and scaffolds for tissue engineering. These materials may also be the next generation of advanced separation media, tough optically clear solids, catalysts or nanocomposites used in the fabrication of nano- or micro-mechanical devices. Thermally-responsive memory devices and complex nanoscopic coatings for cantilever-based sensor devices are particular applications that will be investigated for the 1-, 2-, and 3-dimensional superstructures. Additionally, the proposed materials will be evaluated as nanoscopic surfaces from which the crystallization of inorganic salts or biomacromolecules can initiate. The controlled co-crystallization of the superstructures will be investigated, as a model system for the nanocrystalline phases found in bone growth.